The Clinical/Tissue Core has been an important component of the CSIBD since its inception, serving as the nexus between investigators exploring the etiology and pathophysiology of the inflammatory bowel diseases and patients with these conditions. The Clinical/Tissue Core has supported the needs of researchers both within and external to the CSIBD through a number of highly organized efforts designed to facilitate connections between bench top and clinic, specifically the IBD and control patient base within the MGH Crohn's & Colitis Center and the gastroenterology practice at Massachusetts General Hospital. To date, these efforts have included 1) a clinical database of patients with inflammatory bowel disease seen at the Massachusetts General Hospital, 2) tissue samples, 3) tissue sections, 4) a serum bank, 5) immortalized lymphocytes from IBD probands, as well as their affected and unaffected 1*' degree relatives and 6) clinical research support. These resources have evolved over the duration of the CSIBD as both needs and capabilities have evolved, and will continue to change and adapt over the next 5 years of funding. Within the next 1 to 2 years it is anticipated that the genetic architecture underpinning the inflammatory bowel diseases largely will have been elucidated, with GWAS studies already having identified loci with even modest effect sizes (odds ratios as low as 1.2) in Crohn's disease and ulcerative colitis following a similar trajectory of discovery, although lagging by 1 to 2 years. We anticipate that this remarkable accomplishment will drive the need to revise the focus of the Clinical/Tissue Core in the coming funding period.